Separation process for zirconium and compounds thereof



United States Patent Ofiice 2,892,681 Patented June 30, 1959 SEPARATIONPROCESS FOR ZIRtIONIUM AND COMPOUNDS THEREGF Howard W. Crandall,Berkeley, Calif., and John R. Thomas, Silver Spring, Md., assiguors tothe United States of America as represented by the United States AtomicEnergy Commission No Drawing. Application August 25, 1949 Serial No.112,404

22 Claims. (Cl. 23-88) This invention relates to compounds of zirconiumand to a process for the separation of zirconium from aqueous solutions,and it more especially relates to the separation of zirconium fromcolumbium, rare earths, yttrium and alkaline earth metals.

The present invention also relates to the extraction of zirconium froman organic solvent solution of a zirconium chelate compound.

During neutron irradiation of uranium there are produced in addition tothe transuranic elements, Np and Pu, other elements of lower atomicweight, known as fission fragments. These radioactive fission fragmentsare composed of two distinct groups of elements, namely, a light elementgroup and a heavy element group. The light element group containselements having atomic numbers between about 35 and 46 and the heavierelement group is composed of atomic numbers between about 51 and 60. Theelements of both of these groups as originally produced, beingconsiderably overmassed and undercharged, are highly unstable. By meansof beta radiation they quickly transform themselves into' isotopes ofother elements having longer half-lives. The fission fragments and theresulting decay products are collectively known as fission products.

The various radioactive fission products have halflives that range froma fraction of a second to thousands of years. Those having very shorthalf-lives may be substantially eliminated by aging theneutron-irradiated material for a reasonable period of time beforefurther processing. Those radioactive fission products having very longhalf-lives do not have a sufliciently intense radiation to endangerpersonnel protected by moderate shielding. On the other hand, theradioactive fission products that have half-lives ranging from a fewdays to a few years have dangerously intense radiations which cannot beeliminated by aging for practical storage periods. These fissionproducts are chiefly radioactive isotopes of Sr, Y, Zr, Cb, Ru, Te, I,Cs, Ba, La, Ce, and Pr.

The material from the neutronic reactor contains a total amount offission products that is rarely above 1% by weight of the uranium andusually substantially below this concentration, e.g., one part perthousand parts and even one part per million parts of uranium. In orderto recover a particular fission product, it is necessary to separate itfrom large masses of uranium, from plutonium, and from other fissionproducts. Various processes have been developed for separating uraniumand plutonium from the fission products.

The zirconium isotope Zr is produced as one of the fission products. Itis a fi-emitting isotope with a halflife of 65 days and thusdisintegrates to Cb which is also p-emitting and has a half life of 35days. It disintegrates to M a nonradioactive isotope which occurs innatural molybdenum in the amount of about 16% For use in researchincluding medical and metallurgical research the radioactive isotopes Zrand Cb in pure form are desired.

Zirconium occurs in various ores, principally as ZrO in baddeleyite andas ZrSiO which is called zircon. By various methods aqueous solutions ofzirconium salts are obtained from these ores.

It is an object of the present invention to provide new compounds ofzirconium A second object of this invention is to separate Zirconiumfrom its aqueous solutions.

A third object of the present invention is to separate zirconium fromaqueous solutions containing salts of zirconium and other fissionproducts of uranium.

Another object of this invention is to separate zirconium from anaqueous solution also containing a salt of a rare earth.

A further object of the present invention is to provide a process forthe separation of zirconium from an aqueous solution also containing ayttrium salt.

Still a further object of this invention is to separate zirconium froman aqueous solution also containing an alkaline earth salt. a

-It is also an object of this invention to provide a means forseparating zirconium from an organic solvent solution and especiallyfrom anorganic solvent solution ob tained in the extraction of zirconiumas a chelate from aqueous solutions.

Other objects of this invention will 'be apparent from the descriptionwhich follows:

We have found that a suitable separation of zirconium from an acidicaqueous solution of a tetravalent zirconium salt can be obtained bycontacting the aqueous solution with a certain type of chelating agentalone or as an organic solvent solution to form a zirconium chelatecompound. When the organic solvent is present the zirconium chelatecompound is extracted; otherwise, it is separated by filtration or othersuitable means.

The chelating agent of the present invention is a fluori natedB-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl, and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine. Of course, the R group may containvarious substituents such as halogen groups and nitro groups. It ispreferred that R and R both be fluorine atoms and examples of such aclass of diketones are:

Tnifluoroacetylacetone CHr-C-CHg-F-O F;

Propionyltrifluoroacetone Isovaleryltrifluoro acetoneHeptanoylu'ifiuoroacetone Benzoyltrifluoroacetonep-Fluorobenzoyltrifiuoroacetone p-Phenylbenzoyltrifluoroacetonep-Ethylbenzoyltrifiuoroacetone Examples of suitable fluorinatedp-diketones containing less than three fluorine atoms are:

Difiuoroacetylacetone The efficiency of chelation-extraction is not thesame for all. 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone andtrifluoroacetylacetone are preferred fluorinated fl-diketones to be usedin the process of the present invention.

The organic solvent for the present invention is a substantiallywater-immiscible organic compound which is liquid at the temperature ofcarrying out the process. Examples of siutable types of organic solventsare aromatic hydrocarbons, chlorinated aromatic hydrocarbons,chlorinated parafiinic hydrocarbons and aliphatic ketones. Specificexamples are benzene, toluene, chlorobenzene, hexafiuoroxylene,chloroform, carbon tetrachloride, trichloroethylene and methyl isobutylketone (also known as hexone). Benzene, toluene, hexafluoroxylene andhexone are the preferred solvents.

The acid present in the aqueous solution is a strong inorganic acid. Theacid concentration is at least 0.001 N and preferably at least 0.1 N. Ithas been found possible to chelate-extract zirconium by the process ofthe present invention from aqueous solutions containing a stronginorganic acid in a concentration as high as 12 N by utilizing a higherconcentration of the fluoriuated p-diketone as will be seen from datapresented below. Examples of strong inorganic acids that are present inthe aqueous solution from which zirconium is to be separated are asfollows: nitric acid, hydrochloric acid, perchloric acid, and sulfuricacid. Nitric acid and hydrochloric acid are the preferred acids. Thepreferred acid concentration is between 0.1 and 2 N, especially whenusing the process to separate zirconium from colum'bium, rare earths,yttrium and alkaline earths.

The temperature at which the process is carried out may be variedconsiderably; for example, temperatures of 10 to 60 C. are satisfactory.The preferred temperature is room temperature.

The time of contact between the aqueous solution and the chelating agentor the aqueous solution of the chelating agent of this invention isdependent upon the temperature, the organic solvent, the specificchelating agent and numerous other factors including the efficiency ofcontacting the materials. While a wide range of contact time is suitablea time of at least 15 minutes is preferred.

When the chelating agent, namely, the fiuorinated B- diketone having theformula described above, is used with an organic solvent, theconcentration of the chelating agent may be varied Widely. Theconcentration will depend upon the degree of extraction desired, uponthe concentration of the zirconium salt in the initial aqueous solution,upon the nature and concenration of the strong inorganic acid, and uponthe presence or absence of small amounts of water-soluble complexingagents for zirconium, that is, agents which complex zirconium to formwater-soluble complexes. Some of the strong inorganic acids exhibit amild complexing action upon zirconium thereby producing a lowerdistribution coefficient for zirconium for a particular hydrogen ionconcentration as compared with the coefficient using a noncomplexingstrong inorganic acid like perchloric acid. The effect of the complexingaction of such a strong inorganic acid can be overcome by increasing theconcentration of the fluorinated fl-diketone in the organic solvent. Itis preferred that the concentration of the fluorinated fl-diketone inthe organic solvent be at least 0.01 M and concentrations of at least0.03 M are especially preferred. The efliciency of extraction isincreased with increasing amount of chelating agent and the efficiencyis approximately inversely proportional to the third power of thehydrogen ion concentration.

The ratio of the organic solvent solution to aqueous solution may bevaried considerably, but the preferred range of ratio is between 10:1and 1:10.

Examples of suitable water-soluble salts of tetravalent zirconium thatmay be used as aqueous solutions heretofore defined are as follows:zirconyl chloride and zirconium nitrate. Of course, when thesetetravalent zirconium salts are present in low concentrations,especially in tracer concentrations, such as concentrations of the orderof 10- to 10 M, the ionic species of zirconium has been found to beZr(OH)+ at acidities of about 0.005 N and higher and Zr(OH) or ZrO+ atlower acidities. In aqueous solutions having acid concentrations of lessthan 0.1 N there is considerable zirconium loss from solutions byhydrolyzing of zirconium; therefore, an acidity of at least 0.1 N ispreferred.

The new compounds of zirconium of this invention are compounds oftetravalent zirconium and the fluorinated fi-diketones. They arerepresented by the following general formulas:

wherein R, R and R represent the'same groups as indicated above for thegeneral formula of the chelating agent. It is seen that there are twopossible formulas for the zirconium chelate compounds, since thep-diketone may enolize in either of two ways. In either case, zirconiumis bonded to the oxygen atoms by a covalent bond and a coordinate bondand due to resonance the two compounds would be identical. Thesecompounds are solids which have a negligible solubility in water, andwhich are soluble in benzene, toluene and other organic solvents. Thesolubility of zirconium chelate compound of 2-thenoyltrifluoroacetone atvarious temperatures has been studied and the data are presented belowin the examples of the process. These chelate compounds are destroyed byaqueous solutions containing agents that form water-soluble complexeswith zirconium, e.g., oxalic acid and hydrofluoric acid. These chelatecompounds or coordination compounds of tetravalent zirconium and thefluorinated ,B-diketones are colored and those of natural-ocourring ornonradioactive zirconium may be used to form decorative coatings.

In one embodiment of this invention the zirconium chelate compound isprepared by contacting an aqueous solution containing a tetravalentzirconium salt with a fluorinated B-diketone of the type described aboveor with an organic solvent solution of the fluorinated fi-diketone.

In this embodiment the amount of fluorinated B-diketone used ispreferably less than the stoichiometric amount for the formation of thetetravalent zirconium chelate compound so that the latter when formedwill not be contaminated with excess fluorinated B-diketone whenprecipitated from the aqueous solution or when extracted from theaqueous solution where organic solvent is used. The aqueous solutionused in this embodiment contains the strong inorganic acid in theconcentration described above. Other conditions such as the ratio oforganic solvent solution and aqueous solution are those mentioned above.When the fiuorinated fi-diketone is used alone the precipitated chelatecompound is separated by settling, centrifugation, filtration or othersuitable means. When an organic solvent solution offluorinated/S-diketone is used the resultant aqueous phase and organicsolvent extract phase are separated, e.g., by settling orcentrifugation, and the organic solvent extract phase contains azirconium chelate compound of the fluorinated ,B-diketone.

In the second embodiment of the present invention zirconium is separatedfrom aqueous solution containing the tetravalent zinconium salt bycontacting the aqueous solution as described in the first embodiment.The amount of fluorinated fl-diketone is preferably much greater thanthe stoichiometric amount for the formation of tetravalent zirconiumchelate compound. In this embodiment the conditions described above foracidity of the aqueous solution, temperatures, etc. are used.

The zirconium may be separated from the organic solvent solution ofzirconium chelate compound by contacting the solution with an aqueoussolution containing an agent which converts zirconium of the chelatecompound to a water-soluble, organic-insoluble compound and separatingthe resultant organic solvent phase and aqueous extract phase containinga zirconium compound. The volume ratios of organic solvent solution andaqueous solution and other conditions may be varied as in the case ofthe first embodiment. Examples ofcomplexing agents suitable forconverting zirconium into water-soluble complexes are hydrofluoric acidand oxalic acid. The concentration of complexing agent can be variedwidely, e.g., between 1X10" to 1 M, and it varies with the particularagent, the zirconium concentration in the organic solvent solution fromwhich it is to be extracted, and the total amount of free and combinedfluorinated p-diketone.

The zirconium may also be separated from the organic solvent solution oftetravalent zirconium chelate compound by diluting the organic solventsolution with an additional quantity of organic solvent to provide amaximum concentration of free and combined fiuorinated fl-diketone ofless than 0.01 M and contacting the resultant diluted solution with anaqueous solution containing at least 1 N strong inorganic acid andpreferably at least 2 N strong inorganic acid. It is also preferred thatthis aqueous solution contain a complexing agent of the type describedabove to enhance the extraction of zirconium into the aqueous solution.The aqueous extract phase and organic solvent phase are separated bysettling or centrifugation.

In a third embodiment of this invention zirconium is separated from itsaqueous solution by contacting the aqueous solution of the typedescribed above with a chelating agent of this invention in the absenceof an organic solvent and at a temperature above the melting point ofthe B-diketone. The amount of the fluorinated fl-diketone chosen is aconsiderable excess so that excess fl-diketone acts as a solvent for thezirconium chelate compound.

In a fourth embodiment of this invention zirconium is separated from anaqueous solution containing salts of tetravalent zirconium and anothermetal, such as pentavalent columbium, yttrium, rare earths in thetrivalent state, alkaline earths, or mixtures thereof. The aqueoussolution, of course, contains the strong inorganic acid in theconcentration described above and preferably 0.1 to 2 N. Otherconditions are those of the second embodiment.

Another embodiment comprises separating zirconium from an organicsolvent solution of a zirconium chelate compound of a fluorinatedS-diketone of the formula presented above. The process of thisembodiment is described in the second embodiment in conjunctiontherewith as a complete extraction and re-extraction process.

The following examples taken alone and in combination illustrate theembodiments of this invention.

EXAMPLE 1 Table I Element: Distribution of coeflicient 1 ZirconiumPlutonium 26 Columbium 0.054 Strontium 0.0077 Yttrium 0.007 1 Cerium(trivalent) 0.0006

1 Distribution coefiicient is the ratio of concentration of the metalvalue in organic solvent and aqueous phases.

EXAMPLE II A solution of 1 M Z-thenoyltrifluoroacetone in anhydrousbenzene was allowed to evaporate in contact with a quantity of a 0.1 Mzirconyl chloride in 5 N perchloric acid to provide the stoichiometricamount of zirconium assuming the chelate compound formed contained fourB-diketone groups united with one atom of zirconium. The productobtained was filtered and washed with water to remove excess salt andacid. The product was then washed with benzene to remove any excessZ-thenoyltrifluoroacetone and air was drawn through the filter toevaporate the residual benzene. The product was dried at roomtemperature over a desiccant. A 0.2097-g. sample of the product wasanalyzed by moistening with concentrated sulfuric acid followed byignition to zirconium dioxide. Zr found was 0.0262 g., which is inagreement with the calculated weight for ZrO of 0.0265 g., assuming thechelate compound or complex produced was obtained by the substitution ofone hydrogen atom in each of 4 molecules of 2-thenoyltrifluoroacetonewith one atom of zirconium, i.e., assuming the compound was zirconiumtetrakis(2-thenoyltrifluoroacetonate).

The solubility of this zirconium chelate compound in benzene at varioustemperatures was determined by rotating a quantity of the chelatecompound at each temperature with about 7 ml. of the solvent in aconstant temperature bath for five to twenty hours and then removing a-ml. sample through a cotton filter for analysis. More solvent was thenadded to the remaining portion of the tetravalent zirconium chelatecompound of 2-thenoyltrifiuoroacetone and the process was repeated untilconsistent values were obtained as shown by the analyses. The analysesof zirconium chelate compound dissolved in the benzene were made byevaporating the 5-ml. samples in vacuo, weighing to obtain total solute,moistening it with sulfuric acid, igniting, and weighing the 210obtained. The results are presented below in These data calculatedconcentrations for the chelate compound in benzene of 0.018, 0.026, and0.038 M for 20, 30, and 40 C. respectively.

The foregoing description and data illustrate one method of preparingthe tetravalent zirconium chelate compounds of the present invention andillustrate the solubility of this type of compound in an organicsolvent.

A similar study of the solubility of the chelate compound in anhydrousbenzene containing various concentrations of Z-thenoyltrifluoroacetoneat 20 C. and in water-saturated benzene at 20 C. was carried out. Thesolubility data were substantially the same as the value of 10.7 mg.calculated as ZrO /5 ml. presented above, for example, the solubility in0.08 M 2-thenoyltrifluoroacetone solution in anhydrous benzene was 10.9mg. calculated as ZrO /5 ml.

EXAMPLE III A 0.086 M zirconyl chloride solution in 5 N perchloric acidwas treated with various benzene solutions of 2-thenoyltrifluoroacetone.Distribution coefiicients for zirconium between organic and aqueousphases as high as 161 were obtained.

EXAMPLE IV In some of the following experiments tracer concentrations ofradioactive zirconium were used. In other experimentsmacroconcentrations of nonradioactive zirconium were used. The inactivezirconium used was ZrOCl .6H O which was recrystallized several timesfrom concentrated hydrochloric acid to give relatively large needles ofpure white ZrOC] .8I-l O. This salt was used to prepare an aqueoussolution containing 0.1 M Zr(IV) in l N perchloric acid, thus making thesolution 0.2 M in chloride ion. The solution was clear, giving only aslight Tyndall beam, and remained so over a period of several months.The radioactive zirconium used was quite pure, except for columbiumproduced by zirconium disintegration. The zirconium was furtherseparated from the colmnbiurn by providing a 1 N nitric acid solutioncontaining the radioactive zirconium, extracting the zirconium into abenzene solution of 2-thenoyltrifluoro acetone and washing the benzenephase with 2 N perchloric acid. The benzene solution was diluted tenfoldwith benzene and the zirconium was re-extracted'by a small volume of 2 Nperchloric acid.

The following experiments were carried out by mixing 25 ml. each of anaqueous solution and a benzene solution of 2-thenoyltrifluoroacetone ina -ml. flask using vigorous shaking while in a 25 C. constanttemperature bath.

In the experiments using macroconcentrations of zirconium a colorimetricmethod of zirconium analysis of aqueous phase using alizarin fordetermining zirconium was used. The reproducibility of the alizarinmethod of analysis was of the order of 3%. In the experiments usingtracer concentrations of zirconium the analyses for zirconium werecarried out using usual radioactive counting methods. Aliquots from bothaqueous and solvent phases, usually 0.1 ml., were counted on glass coverslides using a Geiger counter or a vibrating reed electrometer equippedwith a recording potentiometer.

Table III presented below shows the effect of increasedZ-thenoyltrifiuoroacetone concentration in the benzene upon the increaseof the zirconium distribution coefficient. The aqueous solution usedcontained 2 N perchloric acid and a tracer concentration of Zr(IV) salt.

Table III Zr Distribution Ooefiicient l H thnooco s w-canoe wmuswcrenmm1 See footnote to Table I for definition.

Table IV below presents the data on the study of the effect of varyingthe Zr(IV) concentration on the extraction coefficient using 2 Nperchloric acid and using 0.01 M 2-thenoyltrifluoroacetone solution inbenzene. The coeflicients are corrected in the third column to thevalues that would be obtained if the free p-diketone concentration werethe same in the other experiments as in the tracer experiment.

These data show that the extraction is substantially unefiected by avariation in the zirconium concentration in the aqueous solution fromwhich it is chelated-extracted. Of course, the distribution coefiicientcan be increased by increasing the concentration of iluorinatedfl-diketone in the organic solvent; for example, using a benzeneso1ution containing 0.04 M Z-thenoyltrifluoroacetone and 2 N perchloricacid containing about 0.003 M Zr(IV) a zirconium distributioncoeflicient (organic solvent/aqueous) of about were obtained.

Table V presents data from the experiments studying. the dependence ofzirconium extraction or distribution on the hydrogen ion concentration.The data were obtained using aqueous solutions containing tracerconcentrations of Zr(IV) at 25 C. V V

9 Table V Zr Distribution Coefliclent 1 1 See footnote of Table I fordefinition.

The gamma counts per minute in the aliquot of the benzene phase for theexperiments using an aqueous solution containing 0.012 perchloric acidand 0.0012 M 2- thenoyltrifluoroacetone in benzene were 2,950 ascompared with 70 beta counts per minute in the aliquot of the aqueousphase. Using these analyses the zirconium distribution coeflicient wasdetermined to be 42.5. These data also illustrate the concentration ofthe tracer solution used. V

Thezirconium distribution coefiicient between organic and aqueous phaseusing a tracer solution of Zr(IV) containing 0.27 M sulfuric acid andperchloric acid to provide a 2 M total acidity at 25 C. and using abenzene solution containing 0.05 M 2-thenoyltrifluoroacetone was 0.69.Other data show that the complexing effect of sul-. fate anion, whichreduces the distribution coeificient, can be overcome by providing asutficiently high concentration of fluorinated fi-diketone, such asZ-thenoyltrifluoroacetone. I

In Table VI below the zirconium distribution coeflicients are presentedto show the very marked effect of hydrofluoric acid upon the zirconiumdistribution coefiicient. These data were obtained using 'a tracersolution of Zr(IV) containing 2 N perchloric acidiat 25 C. and benzenesolutions of Z-thenoyltrifluoroacetone.

. See footnoteoi Table I for definition.

' The foregoing data show zirconium can be extracted by contacting theorganic solvent'solutio'n of the tetravalent zirconium chelate compoundof fluorinated fi-diketone with an aqeuous solution containinghydrofluoric acid. The degree of extraction is dependent upon the HFconcentration and dependent upon the total concentration of free andcombined fluorinated fi-diketone in the organic solvent.

EXAMPLE V A uranium slug from a neutronic reactor was dissolved innitric acid to provide a solution containing 2.3 M uranyl nitrate and0.33 N nitric acid. The solution contained a small amount of plutoniumand about 0.1 curie of beta and gamma radiation per ml. The solution wasstored for 100 days from the time that the slug was removed from theneutronic reactor. The distribution of beta activity was calculated tobe approximately as follows: 26% Ce, 26% Sr, 23% Y, 12% Zr, 3.5%

Ru, 3.2% Cb, as counted through 11 mg./cm. total absorber. One ml. ofthis solution was mixed with 1 5 ,B-diketone under these radiationconditions.

of 0.5 M Z-thenoyltrifluoroacetone in benzene. Aliquots of the benzenelayer were removed at various time intervals and2-thenoyltrifluoroacetone analyses were carried out to determine thestability of the fluorinated The mixing time was a total of 45 hours.The Z-thenoyltrifluoroacetone analyses indicated that the compound wasstable under these radiation conditions.

EXAMPLE VI A series of experiments was carried out in which benzene andhexone solutions of 2-thenoylt1ifluoroacetone were agitated with aqueoussolutions having the nitric acid concentrations indicated in Table VIIpresented below. In some of these experiments zirconium tracer wasinitially present as chelate compound in organic solvent and in otherexperiments it was initially present in the aqueous solution. Theinitial aqueous solution in the first and second experiments alsocontained 2.3 M uranyl nitrate. The initial aqueous solution in thethird and fourth experiments contained 3'N sulfuric acid. In the fifthexperiment the aqueous solution contained 0.09 M oxalic acid. In thelast three experiments the aqueous solutions contained aluminum nitratein a concentration of 0.75, 0.7; and 0.7 M respectively.

In the first experiment in Table VII the equilibrium was reached intwominutes. In the second experiment only of equilibrium was reached insix minutes, but before fourteen minutes complete equilibrium wasattained. The data of the table show the extraction and re-extraction ofprocess of the present invention using benzene and hexone. It was foundrfrom these and other experiments that the concentration of2-thenoyltrifluoroacetone in hexone required to attain the same level ofextraction of Zr(IV) was three to four times as high as theconcentration in benzene. I

EXAMPLE VII A series of extraction experiments of zirconium from benzenesolution of the tetravalent zirconium chelate compound of2-thenoyltrifluoroacetone and containing 0.1 M Z-thenoyltriflnoroacetoneusing various aqueous media was carried out. Equal volumes and a mixingfor twenty minutes were used in each case. The data are presented inTable VIII.

Table VIII Diketone Cohen, Zr Distri- M v Aqueous Solution butionCoefficient 1 0. H2O 81 0. 1 N H 0. 04 0. 2 N H 0. 03 0. 9.6 N HNOa0.006 0. 0.1 M H2020; and 2 N H0103... 0. U1 0. H1O. 249 0. l M H0 1070. 0.1 M H2020 I. I 0. 0.5 N HF 0. 09 1 H1O 1---. 0.5 N HNOs--- 182 1 1N HNO; 60

l See footnote of Table I for definition.

- These data show that the chelate compound of this invention can beextracted by diluting the organic solvent solution to provide a totalchelate agent concentration of 0.01 M or less and/or by using complexingagents, such as oxalic acid and hydrofluoric acid.

EXAMPLE VIII Aqueous solutions containing 0.5 N nitric acid andindividual tracer concentration of radioactive metal salts were mixed ineach case with an equal volume of 0.03 M 2-thenoyltrifluoroacetonesolution in benzene for fifteen minutes. The extraction data arepresented in Table Tab'le IX Distribution Tracer Element Coetl-lcient 1Ch a. 4 X Zr 1.3 1 X 10% C III ca. R?l ca. 1 X 10 1 See footnote ofTable I for definition.

The data were based upon the determination of the beta activity of thesetracer elements in the organic and aqueous phases at equilibrium.

EXAMPLE IX In a study of the chelation-extraction of tracer zirconiumfrom 2 N nitric acid by agitation for ten minutes by an equal volume ofxylene containing various concentrations of Z-thenoyltrifluoroacetonethe percent zirconium extracted was determined. The data are presentedbelow in Table X.

It was found that the extraction of tracer zirconium from 0.5 to 8 Nnitric acid and from 1 to 12 N hydrochloric acid was between 98 and100%. There was no extraction of tracer zirconium from an aqueoussolution containing 1% oxalic acid, but when the solution also contained10 N hydrochloric acid or 13 N nitric acid the zirconium extraction was50 and 87% respectively.

The process of the present invention may be carried out using batch orcontinuous conditions with equipment commonly used for cocurrent orcountercurrent operation in the continuous process.

The foregoing illustrations and embodiments of this invention are notintended to limit its scope, which is to be limited entirely by theappended claims.

What is claimedis:

l. A process for the separation of zirconium from a mixture containingzirconium, columbium, a rare earth, and an alkaline earth, whichcomprises contacting an aqueous solution containing salts of tetravalentzirconium, pentavalent columbium, a rare earth in the trivalent state,and an alkaline earth and containing at least 0.001 N of a stronginorganic acid with a solution in a substantially water-immiscibleorganic solvent of a fluorinated diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine, and separating the resultantaqueous phase containing said salts of columbium, rare earth, andalkaline earth and organic solvent extract phase containing a zirconiumchelate compound of the fluorinated fi-diketone.

2. The process of claim 1 in which the fluorinated fi-diketone istrifluoroacetylacetone.

3. 'I'he process of claim 2 in which the organic solvent is benzene.

4. The process of claim 1 in which the fluorinated S-diketone isbenzoyltrifiuoroacetone.

5. The process of claim 1 in which the fluorinated fi-diketone is2-thenoyltrifiuoroacetone.

6. The process of claim 5 in which the organic solvent is benzene.

7. The process of claim 1 in which the fluorinated fi-diketone isZ-thenoyltrifiuoroacetone and in which the organic solvent is xylene.

8. The process of claim 1 in which the fluorinated ,B-diketone is2-thenoyltrifluoroacetone and in which the organic solvent is hexone.

9. The process of claim 1 in which the inorganic acid is nitric acid andthe concentration is between 0.1 and 2 N.

10. The process of claim 1 in which the inorganic acid is hydrochloricacid and the concentration is between 0.1 and 2 N.

11. A process for the separation of zirconium from a mixture containingzirconium, columbium, a rare earth, and an alkaline earth, whichcomprises contacting an aqueous solution containing salts of tetravalentzirconium, pentavalent columbium, a rare earth in the trivalent state,and an alkaline earth and containing at least 0.001 N of a stronginorganic acid with a solution in a substantially water-immiscibleorganic solvent of a fluorinated fi-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine, separating the resultant aqueousphase containing said salts of columbium, rare earth, and alkaline earthand organic solvent extract phase containing a zirconium chelatecompound of the fluorinated p-diketone, contacting said extract phasewith an aqueous solution containing oxalic acid which converts zirconiumof said chelate compound to a water-soluble, organic solvent-insolublecompound, and separating the resultant organic solvent phase and aqueousextract phase containing a zirconium compound.

12. A process for the separation of zirconium from a mixture containingzirconium and columbium, which comprises dissolving said mixture in anaqueous solution of a strong inorganic acid to provide a solution havingat least 0.001 N acid concentration and salts of tetravalent zirconiumand pentavalent columbium, contacting said solution with a substantiallywater-immiscible organic solvent solution of a fluorinated fl-diketonewherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydro gen and fluorine, and separating the resultantaqueous phase and organic solvent extract phase containing a 13zirconium chelate compound of the fluorinated fi-diketone.

13. The process of claim 12 in which the inorganic acid is nitric acidin a concentration of 0.1 to 2 N, in which the fluorinated ,B-diketoneis trifluoroacetylacetone, and in which the organic solvent is benzene.

14. The process of claim 12 in which the inorganic acid is nitric acidin a concentration of 0.1 to 2 N, in which the fluorinated ,B-diketoneis 2-thenoyltrifluoroacetone, and in which the organic solvent isbenzene.

15. A process for the separation of Zirconium from a mixture containingzirconium and a rare earth, which comprises dissolving said mixture inan aqueous solution of a strong inorganic acid to provide a solutionhaving at least 0.001 N acid concentration and salts of tetravalentzirconium and rare earth maintained in the trivalent state, contactingsaid solution with a substantially water-immiscible organic solventsolution of a fluorinated p-diketone having the general formula:

RCf-OH2C(JZR wherein R is a member of the group consisting of alkyl,aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are membersof the group consisting of hydrogen and fluorine, and separating theresultant aqueous phase and organic solvent extract phase containing azirconium chelate compound of the fluorinated fi-diketone.

16.' A process for the separation of zirconium from a mixture containingzirconium and alkaline earth, which comprises dissolving said mixture inan aqueous solution of a strong inorganic acid to provide a solutionhaving at least 0.001 N acid concentration and salts of alkaline earthand tetravalent zirconium, contacting said solution with a substantiallywater-immiscible organic solvent solution of a fluorinated fl-diketonehaving the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine, and separating the resultantaqueous phase and organic solvent extract phase containing a zirconiumchelate compound of the fluorinated B-diketone.

17. A process for the separation of zirconium from an organic solventsolution of a tetravalent zirconium chelate compound of a fluorinatedB-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicmls and R and R are members of the groupconsisting of hydrogen and fluorine, which comprises contacting saidsolution with an aqueous solution containing oxalic acid which convertszirconium of said chelate compound to a water-soluble, organicsolvent-insoluble compound, and separating the resultant organic solventphase and aqueous phase containing a zirconium compound.

18. The process of claim 17 in which the chelate compound is a compoundof zirconium and Z-thenoyltrifluoroacetone and in which the organicsolvent is benzene.

19. The process of claim 17 in which the chelate compound is a compoundof zirconium and trifluoroacetylacetone and in which the organic solventis benzene.

20. A process for the separation of zirconium from an organic solventsolution of a tetravalent zirconium chelate compound of a fluorinated8-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine, which comprises contacting saidsolution with an aqueous solution containing hydrofluoric acid whichconverts zirconium of said chelate compound to a water-soluble, organicsolvent-insoluble compound, and separating the resultant organic solventphase and aqueous phase containing a zirconium compound.

21. A process for the separation of zirconium from an organic solventsolution of a tetravalent zirconium chelate compound of a fluorinatedfl-d-iketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic radicals and R and R are members of the groupconsisting of hydrogen and fluorine, which comprises diluting saidsolution with solvent to provide a final total free and combinedconcentration of fluorinated ,B-diketone of less than 0.01 M, contactingthe diluted solution with an aqueous solu tion containing at least 1 Nstrong inorganic acid, and separating the resultant organic solventphase and aqueous phase containing a zirconium compound.

22. The process of claim 21 in which the strong inorganic acid is nitricacid and the acid concentration is at least 2 N.

References Cited in the file of this patent UNITED STATES PATENTS2,161,184 McKone et al. June 6, 1939 2,227,833 Hixson et al. Ian. 7,1941 FOREIGN PATENTS 289,493 Great Britain Apr. 30, 1928 OTHERREFERENCES Huffman et al.: The Separation of Zirconium and Hafnium byExtraction With Thenoyltrifluoroacetone, AECD-2387, October 7, 1948, 5pages. Technical Information Branch, Oak Ridge, Tenn.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2 89268l June 30, 1959 Howard W. Crandall et alo It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 7 Table II second column, line 1 thereof for "8206" read 86,2column 12 lines 65 to 70 the formula should appear as shown belowinsiaead of as in the patent:

Signed and sealed this 8th day of October 1963,

(SEAL) Attesti EDWIN Lo REYNOLDS ERNEST W. SWIDER Attesting Officer ACting Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE, OFCORRECTION Patent N0o 2 892 68l June 30 1959 Howard W, Crandall et al,

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 7, Table Il second column,line l thereof for "82.6" read 86,2column 12 lines 65 to 70 the formula should appear as shown below instzead of as in the patent:

Signed and sealed this 8th day of October 1963.,

(SEAL) Attest:

EDWIN Lo REYNOLDS ERNEST W. SWIDER fiesting Officer AC t i n qCommissionQr Patents

